The NH Department of Environmental Services recently released its long-awaited draft Great Bay Non-Point Source Nitrogen Study, providing a breakdown of the sources of nitrogen pollution in the estuary, and additional insights on how to improve and protect water quality.
According to the draft study, the Great Bay estuary receives, on average, a total load of 1,225 tons per year of nitrogen pollution. Of that total load, 390 tons (32 percent) come from sewage treatment plants. The remainder – approximately 900 tons per year – comes from a variety of so-called “non-point” sources: sources of pollution that are less discrete and less concentrated than what many of us may think of as a pipe discharging pollution from a facility. The draft study looked at four major “non-point” inputs of nitrogen pollution – atmospheric deposition, chemical fertilizers, septic systems and animal waste.
The study found that atmospheric deposition accounts for roughly 280 tons of nitrogen pollution annually (23% of the nitrogen load to the estuary). While a large percent of this is from out-of-state sources, such as polluted air from the Midwest, the rest comes from New Hampshire.
We can all help, by taking actions that reduce air pollution – such as by driving less, carpooling, using public transportation, using less electricity, and purchasing power from sources other than PSNH, which continues to operate polluting coal-fired power plants like Portsmouth’s Schiller Station. CLF has joined the empowerNH campaign, which provides information about how you can switch away from PSNH’s dirty, expensive energy and purchase cheaper, cleaner power.
According to the study, chemical fertilizer is another source of nitrogen pollution, adding 30 tons of nitrogen per year, or 18% of the estuary’s total load. Lawns and agricultural areas each contribute about the same amount, while recreational fields, parks and golf courses are only responsible for a small fraction of the total. The message here is clear – agricultural operations need to implement best management practices, and we need to have smaller lawns and use less fertilizer. Learn how you can have a healthy lawn and protect the environment.
Did you also know that more than half of the nitrogen load to the Great Bay estuary comes from human waste?
Human waste from septic systems accounts for 240 tons per year of nitrogen pollution. Add that to the 390 tons per year from sewage treatment plants – the single largest source of nitrogen pollution (and a source that can be easily controlled through sewage treatment upgrades) – and human waste accounts for a whopping 630 tons per year, meaning over half of the total nitrogen load to the estuary comes from human waste.
Animal waste accounts for the remaining 110 tons per year of nitrogen pollution in the estuary, with livestock responsible for most of this total. The rest is from pet waste. While pet waste is not a big part of the problem, reducing the water quality impacts of our pets is something all pet owners can do. Learn about environmentally friendly ways to care for your pet.
According to the study, much of the nitrogen from these non-point sources reaches the estuary through stormwater runoff. This means that in addition to reducing pollution from sewage treatment plants, we have to tackle the difficult challenge of stormwater pollution. Looking forward, it will be essential for communities to adopt “green infrastructure” approaches that reduce runoff, and to promote more compact development patterns as opposed to land-consuming sprawl. Incredibly, as a result of sprawl, impervious surfaces (roads, parking lots and rooftops) in New Hampshire’s coastal watershed increased 120 percent since 1990!
The study also modeled nitrogen loads for individual subwatersheds and towns to identify “hot spots.” These results should be useful in prioritizing efforts to reduce non-point sources of nitrogen and will complement a study being completed by the UNH Water Resources Center to pinpoint many of these hot spots.
Did you find this information useful, interesting, or believe more work needs to be done? Then you can be involved. The Department of Environmental Services is accepting public comments on the draft report until August 16, 2013.
For more information about the Great Bay-Piscataqua Waterkeeper and my work to protect the Great Bay estuary, visit: https://www.clf.org/great-bay-waterkeeper/. You can also follow me on Facebook and Twitter.